Hello there,
While I was setting up a relative simple scene, I have noticed that the portals make my scene darker and also make the render slower.
I always use portals for my interiors and this is the first time I see something like that.
I have attached two images. One with portals on and one with portals off.
The image with portals on took 7 mins and 5 secs to be completed
The image with portals off tool 4 mins and 15 secs.
Light also splotches alot, which is worrying.
If you need the scene I can send it.
Cheers,
Christos